1. Field of the Invention
The present invention relates to a liquid jet head for ejecting liquid from a nozzle to record graphics and characters on a recording medium, or to form a functional thin film thereon. The present invention relates also to a liquid jet apparatus using the liquid jet head, and to a method of manufacturing a liquid jet head.
2. Description of the Related Art
In recent years, there has been used an ink-jet type liquid jet head for ejecting ink droplets on recording paper or the like to record characters or graphics thereon, or for ejecting a liquid material on a surface of an element substrate to form a functional thin film thereon. In such a liquid jet head, ink or a liquid material is supplied from a liquid tank via a supply tube to the liquid jet head, and ink or a liquid material filled into a channel is ejected from a nozzle which communicates with the channel. When ink is ejected, the liquid jet head or a recording medium on which a pattern of jetted liquid is to be recorded is moved to record characters or graphics, or to form a functional thin film in a predetermined shape.
Japanese Patent Application Laid-open No. 2009-196122 describes an ink jet head 60 in which ink channels which are a large number of grooves are formed in a sheet formed of a piezoelectric material. FIG. 20 is a sectional view of the ink jet head 60 illustrated in FIG. 2 of Japanese Patent Application Laid-open No. 2009-196122. The ink jet head 60 has a laminated structure of a substrate 62, a piezoelectric member 65, and a cover member 64. Supply ports 81 are formed in the middle of the substrate 62 and discharge ports 82 are formed so as to sandwich the supply ports 81. The piezoelectric member 65 and a frame member 63 are adhered to a front surface of the substrate 62, and the cover member 64 is adhered to an upper surface thereof.
The piezoelectric member 65 is formed by adhering together two piezoelectric plates 73 in which the directions of polarization are opposite to each other. A plurality of minute grooves which extend in a sub-scanning direction (in a direction in parallel with the drawing sheet) are formed by grinding in the piezoelectric member 65, and a plurality of pressure chambers 74 which are arranged at regular intervals in a main scanning direction (in a direction perpendicular to the drawing sheet) are formed. Each of the pressure chambers 74 (channels) is defined by a pair of adjacent walls 75. An electrode 76 is formed continuously on opposing side surfaces of the pair of walls 75 and a bottom portion therebetween, and further, is electrically connected to ICs 66 via electric wiring 77 formed on the front surface of the substrate 62. The cover member 64 is formed by adhering a film 92 and a reinforcing member 94 together via an adhesive. The cover member 64 is adhered to the piezoelectric member 65 and the frame member 63 under a state in which the reinforcing member 94 is on the piezoelectric member 65 side. Openings 96 and nozzles 72 which correspond to the pressure chambers 74 are formed in the reinforcing member 94 and in the film 92, respectively.
Ink is supplied from the supply ports 81 in the middle of the substrate 62, and flows to the plurality of pressure chambers 74 and then to an ink chamber 90 to be discharged from the discharge ports 82. When a drive pulse is applied from the ICs 66 via the electric wiring 77 to the electrode 76 on the pair of walls 75 sandwiching the pressure chamber 74, the pair of walls 75 undergo shear deformation and bend so as to be spaced away from each other, and then return to their initial positions to increase the pressure in the pressure chamber 74. Thus, an ink droplet is ejected from the corresponding nozzle 72.
In this case, each piezoelectric member 65 has a trapezoidal shape. An electrode is formed on an inclined surface of the trapezoidal shape, and the electrode on the inclined surface electrically connects the electric wiring 77 formed on the front surface of the substrate 62 and the electrode 76 formed on the side surface of the piezoelectric member 65. Further, a plurality of the supply ports 81 for ink supply and a plurality of the discharge ports 82 for ink discharge are formed in the substrate 62. Therefore, the electric wiring 77 is formed on the front surface of the substrate 62 in a route that can skirt those supply ports 81 and discharge ports 82. Japanese Patent Nos. 4658324 and 4263742 and Japanese Patent Application Laid-open Nos. 2010-69855 and 2011-62866 also describe ink jet heads having substantially similar structures. Note that, Japanese Patent Application Laid-open Nos. 2010-69855 and 2011-62866 each describe an ink jet head having two channel rows which are offset in a row direction by a half pitch.
In the ink jet head 60 described in Japanese Patent Application Laid-open No. 2009-196122, the piezoelectric member 65 adhered on the front surface of the substrate 62 needs to be subjected to ramping to form the trapezoidal shape. Further, it is necessary to form conductive films on the inclined surface of the trapezoidal shape, both the side surfaces of the piezoelectric members 65, and the front surface of the substrate 62. Then, it is necessary to electrically separate the conductive films on both the side surfaces to form the electrodes 76, and pattern the conductive film on the substrate 62 to form a large number of electric wirings 77. However, the piezoelectric members 65 are adhered onto the front surface of the substrate 62, and hence a large number of protrusions are present. Further, the conductive film to be processed is inclined. Therefore, a minute process by photolithography and etching is difficult. In Japanese Patent Application Laid-open No. 2009-196122, the electric wirings 77 are formed one by one by laser patterning, and the conductive film on the inclined surface of the piezoelectric member 65 is electrically separated for every inclined surface. Thus, the electrode is processed by a linear process, and hence positioning and the like are complicated and a long period of time is required. Further, the frame member 63 is provided after the electric wirings 77 are formed on the substrate 62, and hence manufacturing steps including positioning, adhering, and processing of the frame member 63, and planarizing of a front surface 94a of the frame member 63 and a front surface of the trapezoidal piezoelectric member 65 become extremely complicated.
Further, in the ink jet head 60 of Japanese Patent Application Laid-open No. 2009-196122, the electric wiring 77 is formed on the substrate 62 on a front surface 92a side which is the ink ejection side, and the IC 66 is mounted on the same side. The cover member 64 comes close to the recording medium, and hence the height of the IC 66 is limited. Further, the IC 66 and a control circuit (not shown) need to be electrically connected to each other by a flexible substrate or the like, but the height thereof is limited also in this case.